A common approach to providing high-integrity coasting of position and velocity data after loss of a global navigation satellite system (GNSS) position signal in space is to employ a triple inertial reference unit (IRU; also inertial navigation unit (INU) installation whereby each of three IRUs individually produces an accurate hybrid GNSS inertial position solution. However, each IRU may have a latent sensor error, the result of which may be rapid growth in position error after loss of GNSS data. A triple-IRU installation may detect these latent errors, or faults, by voting out the “bad” IRU (e.g., an outlier).
However, cost pressures on original equipment manufacturers (OEMs) are driving the reduction or elimination of expensive or redundant navigation components such as IRUs. Further, changes in GNSS signaling and the regulatory environment will drive newer, more flexible architectures that can accommodate multiple frequencies and multiple satellite constellations. One approach is to replace one or two IRUs of the triple-IRU installation with a lower-cost option such as a GNSS-aided attitude and heading reference system (AHRS). However, such GNSS-aided AHRS are associated with lower-performance inertial sensors and consequently may not be able to “coast” position for more than a few seconds after the loss of GNSS data. As a result, the installation may have too few position solutions to vote out an IRU with a latent fault, as described above.